pH Sensing by Intracellular Salmonella Induces Effector Translocation

Abstract

Cytosol, Salmonella , and pH Salmonella and other bacterial pathogens grow inside animal host cells within intracellular vacuoles. The bacteria secrete effector proteins across the vacuole membrane, altering the host-cell physiology to the pathogen's advantage. The secretion process involves a specialized secretory apparatus, the type III secretion system, whose assembly is triggered by the low pH within the host-cell vacuole. Now, Yu et al. (p. 1040 , published online 15 April; see the Perspective by Collier ) have identified neutral pH as a physiological signal for effector translocation by intracellular Salmonella . The process involves the disassembly of a membrane-bound regulatory complex that is also found in other animal pathogens. Thus, Salmonella exploits the low pH of the vacuole as a signal to induce assembly of the secretion system, and then the neutral pH of the cytoplasm to trigger effector translocation.